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The present invention is directed to the field of test instruments and test apparatus for determining properties of material. More particularly, the present invention is concerned with a novel moisture tester for determining the moisture content of any of a plurality of different grain or grain-like materials.
Since grain moisture is defined as a percentage by weight of moisture, it is necessary to use a sample of known weight in order to obtain an accurate moisture reading. Some prior art systems have accomplished this by separately weighing out a test sample prior to introduction thereof into a test instrument. However, this procedure is somewhat cumbersome and time consuming.
One particularly useful and successful weight-responsive type of moisture tester is shown in U.S. Pat. No. 3,794,911, assigned to the assignee of this application. This weight-responsive moisture tester is arranged to automatically perform the moisture measurement when the weight of a sample introduced into the test apparatus reaches a given, predetermined weight, thereby eliminating a need to separately weigh out the sample prior to testing. Moreover, this novel patented device also utilizes a temperature compensation arrangement to compensate the moisture reading for variations from a standard or reference temperature.
While the foregoing patented device has enjoyed wide-spread acceptance, there is room for yet further improvement. For example, some compensation for the inertia effect of the pouring of material into the apparatus is desirable. The foregoing patented apparatus provided such compensation by utilizing a small built-in time delay to prevent the actual measurement from taking place for a very short period following the sample reaching the desired weight, to attempt to compensate for inertia and to allow the apparatus to stabilize.
We propose to improve upon the foregoing system by additionally providing a built-in warning system, wherein the operator is warned, just prior to reaching the weight at which the measurement is made, to slow the rate of pouring of material into the apparatus somewhat to avoid excessive inertia effects. We have also developed a novel inertia compensation method for further compensating for differences in inertia caused by differences in pouring rate while introducing material into the test apparatus.
We have also found that it is important to confine the forces exerted upon the test apparatus by the material substantially to the vertical direction to assure proper response for weight measurement purposes. Accordingly, we have proposed using novel torsion resisting means for substantially avoiding the pouring of material from exerting a torsioning or twisting motion upon the apparatus.
In addition to the foregoing, the apparatus of the invention also provides improved temperature compensation, which will accurately predict the actual temperature of grain in the apparatus, without regard for the speed with which the grain is introduced into the test apparatus. Moreover, our arrangement determines when the prediction has converged sufficiently to assure a stable and accurate temperature reading and corresponding compensation.
The test apparatus of the invention further includes memory for retaining calibration and other data for the measurement of as many as 12 different materials. More importantly, we have provided a novel low-cost and easy to use infrared programming link built into the test apparatus so that the apparatus may be normalized, configured for a particular set of features and supplied with calibrations as the last step of manufacture. Alternately, the calibration may be done by a dealer, if desired, without making a physical intrusion or alteration of the apparatus and without making electrical connection to the electronic components thereof.